Fixed-bed extraction of β-glucan from cereals by means of pressurized hot water

beta-Glucans were successfully extracted from different cereals (barley, de-starched barley and wheat bran) in a fixed-bed extractor using pressurized hot water (PHW) as solvent, in the range of 110-175 degrees C, at 20 bar. Results were evaluated in terms of extraction yield, molecular weight of the extracted (beta-glucans and products of hydrolysis. Extraction yield was maximized at 155 degrees C, 20 bar and 4 g/min of PHW for the three raw materials. Under these conditions, almost 100% of the initial beta-glucans were extracted after 105 min of operation, and the molecular weight of the extracted beta-glucans was much higher (up to 500 kDa vs. 180 kDa) compared with batch operation, revealing the feasibility of the use of fixed-bed extractors for the beta-glucan extraction. Under these conditions no degradation products, such as HMF, were detected in the extract. Experimental results have revealed that the operation in fixed-bed is adequate for the extraction and fractionation of high molecular weight beta-glucans in a single step operation. (C) 2013 Elsevier B.V. All rights reserved.